JP2003183239A - Low-colored trinitrile mixture and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-colored trinitrile mixture containing 1,3,6- tricyanohexane as a main component, capable of giving various derivatives having improved color, and to provide a method for producing the same. <P>SOLUTION: This low-colored trinitrile mixture is obtained from a mixture which contains the nitrile compound formed in an electrolytic reduction reaction of acrylonitrile as the main component, wherein the mixture contains the trinitrile compound in an amount of ≥85 wt.%, and has a L-value (a brightness index) of ≥97, an a-value (a chromaticness index) of -1.0 to 1.0, and a b-value (another chromaticness index) of -1.0 to 2.0 which are measured in a diethylene glycol dimethyl ether solution at a concentration of 10 g/ml. The method for producing the low-colored trinitrile is provided in the specification. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a trinitrile mixture produced as a by-product during the production of adiponitrile by the electrolytic reduction reaction of acrylonitrile, and in particular, it is mainly composed of 1,3,6-tricyanohexane and has a reduced coloring. And a method for producing the same.

[0002]

2. Description of the Related Art 1,3,6-tricyanohexane is 4
-Aminomethyl-1,8-diaminooctane and 1,3
It is useful as a raw material for 6-hexanetricarboxylic acid.
Among them, 1,3,6-hexanetricarboxylic acid is water-soluble and has good biodegradability, and therefore it has been proposed to be applied to various uses. For example, it has been proposed that 1,3,6-hexanetricarboxylic acid derived from 1,3,6-tricyanohexane or a salt thereof can be suitably used for detergent preparations, chain lubricants and the like (Germany Patent Application Publication No. 19637428). JP-A-4-34274 discloses that 1,3,6-hexanetricarboxylic acid can be suitably used as a plasticizer for a halogen-containing resin having excellent cold resistance by esterification with a higher alcohol.
No. 8 publication.

In developing 1,3,6-tricyanohexane for these applications, its derivative 1,3,6
As a matter of course, the hexanetricarboxylic acid and the esterified product with a higher alcohol are desired to have a low hue without coloring. For example, when 1,3,6-hexanetricarboxylic acid is colored, its esterified product also tends to be markedly colored, and in the case of a high boiling point derivative such as an esterified product with a higher alcohol, distillation purification Etc. is difficult. Further, when decolorizing 1,3,6-hexanetricarboxylic acid, a large purification step is required, such as dissolving the solid compound again in a solvent to perform decolorizing treatment and further removing the solvent used. And

In general, 1,3,6-hexanetricarboxylic acid uses 1,3,6-tricyanohexane as a raw material obtained in the electrolytic reduction reaction of acrylonitrile. The trinitrile mixture with increased purity of 1,3,6-tricyanohexane obtained in the electrolytic reduction reaction usually exhibits remarkably yellow to black coloration. For example, only by distillation purification, 1,3,6- Decolorization of tricyanohexane is insufficient. 1,3,6-
Similarly, 1,3,6-hexanetricarboxylic acid derived from a trinitrile mixture containing tricyanohexane as a main component tends to be markedly colored.

As a method for purifying 1,3,6-tricyanohexane obtained by the electrolytic reduction reaction of acrylonitrile, for example, in JP-A-62-270550, molecular distillation is carried out, and further molecular distillation is carried out. A method of washing with water afterwards has been proposed, and for example, a Hazen value of 400 to 500 has been obtained as the chromaticity. However, the Hazen value of 400 still looks like
It has a considerably yellow color, and for example, when the chromaticness index thereof is measured, the a value is lower than -1, or
The b value is 2 or more. In fact, when such a trinitrile mixture is used to derive 1,3,6-hexanetricarboxylic acid, there is a tendency to obtain only those showing a considerable yellow color.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a low-hue 1,
It is an object to provide a trinitrile mixture containing 3,6-tricyanohexane as a main component, and a method for producing the same.

[0007]

In order to solve the above-mentioned problems, the inventors of the present invention firstly describe the hue of a trinitrile mixture obtained by the electrolytic reduction reaction of acrylonitrile used as a raw material and the derivative obtained from this mixture. The relationship between the hues was eagerly examined. As a result, it has been found that in the trinitrile mixture obtained by the electrolytic reduction reaction of acrylonitrile, the hue of the resulting derivative can be remarkably improved by using the trinitriles having the hues having the lightness index and the chromaticness index in the specific ranges.

Furthermore, the inventors of the present invention have made earnest studies to obtain a low hue trinitrile mixture having the above-mentioned lightness index and chromaticness index in the preferable ranges. As a result, a mixture of nitrile compounds obtained in the electrolytic reduction reaction of acrylonitrile is obtained. On the other hand, it was found that trinitriles having a low hue can be easily obtained by using a solid adsorbent and / or an oxidizing agent, and the present invention has been completed. That is, the present invention is as follows. (1) Obtained from a mixture containing a nitrile compound produced by an electrolytic reduction reaction of acrylonitrile as a main component,
The content of the trinitrile compound in the mixture is 85% by mass or more, the content of adiponitrile is 10% by mass or less, and the lightness index L value of the diethylene glycol dimethyl ether solution having a concentration of 0.10 g / ml is 98 or more, and the chromaness. A low hue trinitrile mixture having an index a value of -1.0 to 1.0 and ab value of -1.0 to 2.0. (2) 1,3,6-tricyanohexane content is 85
The low hue trinitrile mixture according to (1), which is contained in an amount of not less than mass%. (3) A nitrile mixture containing adiponitrile as a main component is produced by an electrolytic reduction reaction of acrylonitrile in the presence of an electrolyte, and then adiponitrile is removed from the mixture until the adiponitrile content rate is 10% by mass or less. By removing the components having a higher boiling point, the content of the trinitrile compound can be increased to 8
A process for producing a low hue trinitrile mixture, which comprises treating a nitrile mixture in an amount of 5% by mass or more with an oxidizing agent. (4) A nitrile mixture containing adiponitrile as a main component is produced by an electrolytic reduction reaction of acrylonitrile in the presence of an electrolyte, and then adiponitrile is removed from the mixture until the adiponitrile content is 10% by mass or less. By removing the components having a higher boiling point, the content of the trinitrile compound can be increased to 8
A process for producing a low hue trinitrile mixture, which comprises treating a nitrile mixture in an amount of 5% by mass or more with a solid adsorbent. (5) A nitrile mixture containing adiponitrile as a main component is produced by an electrolytic reduction reaction of acrylonitrile in the presence of an electrolyte, and then adiponitrile is removed from the mixture until the adiponitrile content is 10% by mass or less. By removing the components having a higher boiling point, the content of the trinitrile compound can be increased to 8
A method for producing a low hue trinitrile mixture, which comprises treating a nitrile mixture in an amount of 5% by mass or more with a solid adsorbent and an oxidizing agent. (6) The method for producing a low hue trinitrile mixture according to (3) or (5), wherein the oxidizing agent is ozone or hydrogen peroxide.

The present invention will be described in detail below. The electrolytic reduction reaction of acrylonitrile produces various nitrile compounds in addition to the main product, adiponitrile.
This reaction solution also contains unreacted acrylonitrile. Examples of by-products include trimers such as propionitrile, α-methylglutaronitrile, hydroxypropionitrile, succinonitrile, and acrylonitrile, and further high molecular weight substances in which acrylonitrile is a tetramer or more.

In the electrolytic reduction reaction of acrylonitrile, it is possible to obtain a non-negligible amount of an acrylonitrile trimer containing 1,3,6-tricyanohexane as a main component and a tetramer or higher polymer. , Journal of
Organic Chemistry (J. Org. Che
m. ), 30 (5) 1351 (1965). Generally, the main component of the trinitrile compound, which is a trimer of acrylonitrile produced by the electrolytic reduction reaction of acrylonitrile, is 1,3,6-tricyanohexane, and the other isomer, 3-cyanomethyl-1,5
-A small amount of dicyanopentane etc. is contained. The trinitrile compound in the present invention means a trinitrile compound which is a trimer of acrylonitrile produced by the electrolytic reduction reaction of these acrylonitriles.

The trinitrile mixture of the present invention is acrylonitrile obtained by removing low boiling components such as acrylonitrile and adiponitrile and high molecular weight components of tetramer or more of acrylonitrile from a mixture of the above nitrile compounds by distillation under reduced pressure. It is a mixture containing 85% by mass or more, and preferably 90% by mass or more of a trinitrile compound which is a trimer. Content of trinitrile compound is 85% by mass
If the amount is less than 15% by weight, the above-mentioned low-boiling components exceeding 15% by mass, high molecular weight polymers of acrylonitrile tetramers or more, and coloring components in amounts that are difficult to quantify are contained. Therefore, for example, when a trifunctional carboxylic acid compound or an amine compound is derived from the trinitrile mixture by a hydrolysis reaction or a hydrogenation reaction, the purity of the product is lowered and further the purity is improved, It is necessary to go through various purification steps as a subsequent step, resulting in a decrease in the yield of the derivative.

In the trinitrile mixture of the present invention, 1,
The content of 3,6-tricyanohexane is preferably 8
It is 0 mass% or more, more preferably 85 mass% or more, and most preferably 90 mass% or more. When the content of 1,3,6-tricyanohexane is less than 80% by mass, 1,
The purity and yield of the compound derived from 3,6-tricyanohexane are likely to decrease. In addition to this, the trinitrile mixture of the present invention usually contains 3-cyanomethyl 1,5-dicyanopentane in the range of 0.01 to 10% by mass. In the present invention, the content of this compound is not limited, but when the derivative of 1,3,6-tricyanohexane is obtained with high purity and high yield, it is preferably 0.0
It is 1 to 5% by mass, and more preferably 0.01 to 1% by mass.

The trinitrile mixtures according to the invention are distinguished by their hue. That is, the trinitrile mixture of the present invention has diethylene glycol dimethyl ether as a standard substance, a diethylene glycol dimethyl ether solution having a concentration of 10 g / ml, a lightness index L value measured at 25 ° C. of 98 or more, and a a of the chromaticness index a.
The value is -1.0 to 1.0 and the b value is -1.0 to 2.0. When the hue of the trinitrile mixture is in these ranges, the Hazen value is usually 300 or less.

The L value, a value and b value used in the present invention are measured by a transmission method in the wavelength range of 380 to 780 nm of standard light C using a spectrophotometer according to the method of JIS standard Z8722. Based on the tristimulus values X, Y, and Z values in the XYZ system, the color difference formula of the Hunter shown in the following formula defined by JIS standard Z8730 is used for calculation. L
The values are called lightness index in Hunter's color difference formula, and a and b are called chromaticness index in Hunter's color difference formula.

L = 10Y ^0.5 a = 17.5 (1.02X−Y) / Y ^0.5 b = 7.0 (Y−0.847Z) / Y ^0.5 (where X, Y, and Z are XYZ) Generally, the L value, which is the lightness index, has an upper limit of 100, and as the value increases, the hue of the substance to be measured increases in whiteness, and as the value decreases, the degree of blackness decreases. Means increase. The value a, which is the chromaticness index, is 0.
When the numerical value becomes negative, the hue of the substance to be measured means greenness, and when it becomes positive, it means that the redness increases. The b value, which is a chromaticness index, means that the hue of the substance to be measured increases the blueness when the numerical value becomes negative and the yellowness increases when the numerical value becomes positive, based on 0. That is, the closer the L value is to 100, and the closer the a value and the b value are to 0, the lower the hue.

The trinitrile mixture of the present invention has an L value of 9
8 or more, preferably 99 or more, and a value of -1.0 to
1.0, preferably in the range of -0.5 to 0.5, and the b value is-.
1.0 to 2.0, preferably -1.0 to 1.5, more preferably -1 to 1.0, most preferably -0.5 to 0.
The range is 5. In the trinitrile mixture, L value,
When the a value and the b value deviate from the above ranges, for example, an amide compound or a carboxylic acid compound obtained by hydrolyzing a trinitrile mixture with an inorganic acid or an inorganic basic compound is markedly colored, and its use is limited. On top of
It requires a purification step that is more difficult to decolorize.

The method for producing the low hue trinitrile mixture of the present invention will be described below. The mixture containing a nitrile compound as a main component in the present invention is obtained by an electrolytic reduction reaction of acrylonitrile. The electrolytic reduction reaction of acrylonitrile is carried out by using a so-called diaphragm electrolyzer, which is made of acrylonitrile as a raw material and comprises a cathode chamber and an anode chamber in which a pair of cathode and anode are partitioned by a cation exchange membrane. It is also possible to use a single electrolytic cell without a membrane. These electrolysis methods are disclosed, for example, in JP-B-45-24128, JP-A-59-59888, and JP-A-59-18.
It is disclosed in Japanese Patent No. 5788.

For example, electrolysis using a diaphragm electrolyzer is carried out as follows. Generally, a cathode having a high hydrogen overvoltage can be used as the cathode, and for example, lead, cadmium, and an alloy containing these as the main components are preferably used. The anode is preferably made of lead, lead alloy, platinum or the like having high corrosion resistance, and lead or lead alloy is preferably used. A cation exchange membrane is generally used as the diaphragm, and a sulfuric acid aqueous solution is used as the anolyte. The catholyte consists of acrylonitrile, adiponitrile, trinitrile compounds, other by-products, water, and a conductive supporting salt during the reaction, either as an emulsion separated into an oil phase and an aqueous phase or by excess of acrylonitrile. It is a homogeneous solution or is in either state.

The conductive supporting salt has the following general formula [NR ¹ R ² R ³ R ⁴ ] ⁺ X ⁻ (wherein R ¹ , R ² and R ³ are alkyl groups having 1 to 5 carbon atoms,
R ⁴ is an alkyl group having 1 to 16 carbon atoms, X ⁻ is sulfuric acid, carbonic acid,
It is a residue of an anion such as alkyl sulfuric acid or phosphoric acid, or an organic acid or an organic polyvalent acid. The quaternary ammonium salt represented by the formula (1) is usually preferably used. The pH of the catholyte is usually in the range of 5-12.

The temperature of the electrolytic solution in the battery case during the electrolytic reduction reaction is usually in the range of 40 to 60 ° C., and the current density is
It is usually in the range of 5 to 50 amps per 1 dm ^{2 of the} cathode surface. The distance between the cathode and the anode is usually 1 to 20 mm through the diaphragm, and the catholyte and the anolyte are respectively
Usually, it is passed at a linear velocity of 0.1 to 10.0 m / sec.
When the electrolytic reduction reaction of acrylonitrile is carried out using a single electrolytic cell without an ion exchange membrane as a diaphragm, lead, cadmium, mercury or an alloy containing at least one of these is preferably used as the cathode, and the anode As the material, iron, nickel, or an alloy thereof is used. The electrolytic solution contains an alkali metal salt, the quaternary ammonium salt and water as main components, and during the reaction, the electrolytic solution contains acrylonitrile, adiponitrile,
The trinitrile compound and other by-products exist in the state of emulsion or homogeneous solution. Examples of the cation of the alkali metal salt include lithium, sodium, potassium, rubidium, and the like, and the anion is an inorganic salt of phosphoric acid, boric acid, carbonic acid, sulfuric acid, or the residue of a polyvalent acid.

In the present invention, there is no limitation on the method for obtaining a nitrile mixture containing 85% by mass or more of a trinitrile compound from the electrolytic solution after completion of the above reaction, and it can be obtained by a general extraction method, a distillation method, or a combination thereof. it can. That is, when the electrolytic solution after completion of the electrolytic reduction reaction is an oil-water emulsion, the low-boiling components such as unreacted acrylonitrile and by-product propionitrile are distilled off, and then the emulsion is broken to obtain two layers of oil-water. To separate. Inorganic substances and quaternary ammonium salts are distributed to the water layer, and some water, low-boiling components, adiponitrile, trinitrile compounds and other high-boiling components are distributed to the oil layer.

On the other hand, when the electrolytic solution after completion of the electrolytic reduction reaction is a uniform solution, for example, water and a non-aqueous organic solvent such as methylene chloride are added, and an inorganic salt or a quaternary ammonium salt is added to the aqueous layer. And an adiponitrile, a trinitrile compound, and other high boiling components are extracted into the oil layer. In each case, the water layer and the oil layer are separated, and the low boiling point component such as adiponitrile in the oil layer is removed by a general distillation method to obtain a high boiling point residue containing a trinitrile compound. Usually, this high-boiling-point residue includes adiponitrile, which was not completely removed by distillation, and tetra- or higher-boiling substances of acrylonitrile having a higher boiling point than the trinitrile compound.

In the present invention, adiponitrile is removed until the content of adiponitrile in the nitrile mixture is 10% by mass or less. When the proportion of the trinitrile compound in the high boiling point residue is less than 85% by mass, for example, the low boiling point and high boiling points such as adiponitrile are removed, and the content of the trinitrile compound becomes 85% by mass or more. Repeat distillation until. At this time, for example, JP-A-62-270550
A molecular distillation method and a thin film distillation method as described in Japanese Patent Publication No. 1994-242242 can also be suitably used. Further, in the present invention, for the purpose of adjusting the content rate of the trinitrile compound to 85% by mass or more, the high boiling point residual is extracted with a solvent that selectively dissolves the trinitrile compound, and the subsequent step is performed. A trinitrile mixture can also be obtained by removing the solvent.

The trinitrile mixture used in the present invention has a content of adiponitrile of 10% by mass or less and a trinitrile compound content of 85% by mass in the trinitrile mixture obtained by the method described above.
The above is a high-purity trinitrile mixture. The trinitrile mixture produced by the above method usually has a hue having an L value of less than 98, an a value of less than -1, or a b value of more than 2.

The present invention is characterized in that such a trinitrile mixture is treated with an oxidizing agent, a solid adsorbent, or a combination thereof to produce a low hue trinitrile mixture. . The oxidizing agent used in the production method of the present invention means a compound that generally gives oxygen to an organic substance, a compound that deprives hydrogen of the organic substance, or a compound that increases the positive oxidation number. Specifically, permanganic acid and salts thereof such as potassium permanganate, chromic acid and salts thereof such as potassium chromate, nitric acid, copper nitrate, nitric acid such as ammonium nitrate and salts thereof, halogen such as chlorine, peracetic acid, Peracids such as perbenzoic acid and salts thereof, fuming sulfuric acid, sulfuric acids such as sulfurous acid and salts thereof,
Oxygen acids and salts thereof such as sodium hypochlorite, metal salts such as copper acetate and bismuth acetate, metal oxides such as manganese dioxide, peroxides such as hydrogen peroxide and t-butyl hydroperoxide, air, oxygen , Oxygen such as ozone, etc., and these oxidizing agents may be used either individually or in combination of two or more in separate steps or simultaneously.

The oxidant used in the present invention is preferably one which has high decolorization efficiency after being treated with the oxidant and is easily removed from the trinitrile mixture after the treatment. Hydrogen and ozone are preferred. In the present invention, the treatment with the oxidizing agent is achieved by directly contacting the oxidizing agent with the trinitrile mixture. Specifically, when the oxidizing agent used is solid and does not dissolve in the trinitrile mixture, the oxidizing agent is directly added to the trinitrile mixture, for example, a method of dispersing by stirring, or a column is filled with the oxidizing agent. A method of passing the trinitrile mixture through is used. When the oxidizing agent used is a liquid insoluble in the trinitrile mixture, for example, an aqueous solution, it may be added directly to the trinitrile mixture and stirred in an oil-water separated state. When the oxidizing agent used is a gas, a method of directly blowing into the trinitrile mixture may be performed.

The amount of the oxidizing agent used is not limited as long as a low hue trinitrile mixture can be obtained. Usually, 0.001 of the oxidizing agent is added to 100 parts by mass of the trinitrile mixture.
To 100 parts by mass. There is no limitation on the time for carrying out the treatment with the oxidizing agent, and for example, when obtaining the low hue trinitrile mixture of the present invention, it is usually in the range of 1 minute to 500 hours. Further, the temperature when performing the treatment with the oxidizing agent is not limited as long as it is a range in which a trinitrile mixture having a low hue is obtained, and is usually in the range of -20 ° C to 250 ° C, preferably 0 ° C to 150 ° C. More preferably 10 ° C
~ 100 ° C. If the temperature is high, especially above 250 ° C., the trinitrile compound itself may decompose,
The contained coloring component tends to be modified and further colored. Further, when the temperature is low, particularly when the temperature is lower than -20 ° C, the viscosity of the trinitrile mixture tends to be high, and the treatment time with the oxidizing agent tends to be long.

When the treatment with an oxidizing agent is carried out, the atmosphere and pressure are not limited, and the treatment may be carried out under atmospheric pressure or high pressure by an inert gas such as air or nitrogen, or under reduced pressure. In the treatment with the oxidizing agent, the trinitrile mixture used may be diluted with a miscible solvent in which the solubility of the trinitrile mixture is 5% by mass or more,
Further, it may be in a liquid-liquid separated state in which a non-miscible liquid having a solubility of the trinitrile mixture of less than 5% by mass forms a two-liquid layer. Examples of such miscible solvents include ketones such as acetone, alcohols such as methanol, halogenated hydrocarbons such as chloroform and methylene chloride, esters such as ethyl acetate, ethylene glycol dimethyl ether, tetrahydrofuran and the like. Examples thereof include ethers, but not limited thereto. In addition, examples of the immiscible liquid include water.

There is no limitation on the method of separating and removing the used oxidant after the treatment with the oxidant described above.
A trinitrile mixture having a low hue can be obtained by carrying out a known general method such as a filtration method, a drying method, or a reduced pressure method. Next, a method of treating the above trinitrile mixture with a solid adsorbent will be described. The solid adsorbent of the present invention,
It is a substance that maintains the shape of a solid without fluidity at 25 ° C. and a temperature at which it is treated with a trinitrile mixture, and has a surface having an interface that causes forward adsorption. Specifically, oxides and hydroxides of aluminum, iron, titanium, silicon, tin, etc., activated carbon, bentonite, activated clay, diatomaceous earth, zeolites, hydrotalcites, cation exchange resins, anion exchange resins. Etc. Examples of the oxides and hydroxides of aluminum, iron, titanium, silicon, tin and the like include activated alumina, silica gel,
Examples include titanium oxide. In the present invention, activated carbon and ion exchange resins are preferred because they tend to have high decolorization efficiency. These solid adsorbents may be used alone,
Two or more kinds may be mixed and used at the same time or separately.

The treatment with the solid adsorbent of the present invention is achieved by directly contacting the solid adsorbent with the trinitrile mixture. Specifically, there is a method in which the solid adsorbent to be used is added to the trinitrile mixture and dispersed by, for example, stirring, or a method in which the solid adsorbent is packed in a column and the trinitrile mixture is passed through. The amount of the adsorbent used is not limited as long as a trinitrile mixture having a low hue can be obtained.
The range is 0.001 to 100 parts by mass of the solid adsorbent with respect to 0 parts by mass. However, for example, when the solid adsorbent is packed in a column and the trinitrile mixture is passed through, the amount used is not limited to this.

There is no limitation on the time for carrying out the treatment with the solid adsorbent, and for example, in the case of obtaining the low hue trinitrile mixture of the present invention, it is usually in the range of 1 minute to 500 hours.
Further, the temperature is also within a range where a low hue trinitrile mixture can be obtained, and there is no limitation as long as it is a heat resistant temperature range of the solid adsorbent used, and is usually -20 ° C to 250 ° C, preferably 0 ° C to 150 ° C. More preferably, it is in the range of 10 ° C to 100 ° C. When the temperature is high, particularly when it exceeds 250 ° C., the trinitrile compound itself is decomposed, or the coloring component contained therein is modified to tend to be further colored. When the temperature is low, particularly below -20 ° C, the viscosity of the trinitrile mixture tends to be high, and the treatment time with the solid adsorbent tends to be long.

When the treatment with the solid adsorbent is carried out, the atmosphere and pressure are not limited, and the treatment may be carried out under atmospheric pressure or high pressure by an inert gas such as air or nitrogen, or under reduced pressure. In the treatment with the solid adsorbent, the trinitrile mixture is
As in the case of the treatment with the above-mentioned oxidizing agent, the trinitrile mixture may be diluted with a solvent having miscibility such that the solubility of the trinitrile mixture is 5% by mass or more, and the solubility of the trinitrile mixture is less than 5% by mass. It may be in a liquid-liquid separated state in which it is a two-liquid layer made of an immiscible liquid.

Examples of such miscible solvents include ketones such as acetone, alcohols such as methanol, halogenated hydrocarbons such as chloroform and methylene chloride, esters such as ethyl acetate, ethylene glycol dimethyl ether. And ethers such as tetrahydrofuran and the like, but are not limited thereto. Examples of the immiscible liquid include water. After performing the treatment using the solid adsorbent described above, the method of separating and removing the solid adsorbent used is optional, without limitation,
By carrying out a known general method such as a filtration method, a trinitrile mixture having a low hue can be obtained.

The treatment with the oxidizing agent of the present invention and the treatment with the solid adsorbent may be used in combination, and the order of each step is arbitrary. For example, after the treatment with a solid adsorbent such as an ion exchange resin, the treatment may be performed with an oxidizing agent such as ozone.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to Examples. The measuring method used in the present invention is as follows. [Measurement method of trinitrile purity] The purity of the trinitrile mixture is measured by gas chromatography and gel permeation chromatography (hereinafter,
Abbreviated as GPC). The content of the tetramer or higher polymer of acrylonitrile contained in the trinitrile mixture is determined by GPC.

(A) Gas chromatography measurement The measurement is carried out with the following equipment and conditions. Apparatus: Shimadzu Corporation GC-14B Column: GL Science Inc. Manufactured capillary column TC-1 (0.25 mm ID, length 30 m) Carrier gas: He Detection: FID Column temperature condition: 20 ° C./mi after holding at 60 ° C. for 2 minutes
The temperature was raised to 300 ° C. with n and kept at 300 ° C. for 15 minutes. Sample dissolution solvent: 2.0 mg of toluene (b) GPC measurement sample was dissolved in 2.0 g of tetrahydrofuran and filtered with a 0.5 μm filter under the following conditions: Analysis is performed by deploying and detecting in.

Measuring device: HLC-81 manufactured by Tosoh Corporation
20 GPC detector: RI developing solution: tetrahydrofuran developing solution flow rate: 1.0 ml / min Column: TSKgel (registered trademark) G manufactured by Tosoh Corporation
One MHHR-N and two G1000HXL are installed in series Column temperature: 40 ° C. [Measurement method of hue] 0.40 g of trinitrile mixture is dissolved in 4 ml of diethylene glycol ether quantified with a Hall pipette, and the following method is used. UV by transmission method
The measurement is performed, and the L value, the a value, and the b value are obtained from the obtained tristimulus values according to the Hunter equation.

Measuring device: Shimadzu Corporation UV25
00PC sample cell: made of quartz, outer dimensions 12.4 mm x 12.4 m
m × height 45 mm, optical path length 10.0 mm Diethylene glycol dimethyl ether: special grade reagent manufactured by Wako Pure Chemical Industries, Ltd. Measurement temperature: 25 ± 2 ° C. Wavelength range: 380 to 780 nm Wavelength feed rate: Low speed range (about 140 nm / min)

[0039]

Example 1 In a single electrolytic cell, a lead alloy having a current-carrying surface of 1 cm × 90 cm was used as a cathode, a carbon steel having the same current-carrying surface was used as an anode, and the distance between the anode and the cathode was kept at 2 mm. The electrolytic solution forms an emulsion with 10 parts by mass of an oil phase and 90 parts by mass of an aqueous phase, and the composition of the aqueous phase is about 2.0% by mass of acrylonitrile, about 10% by mass of K ₂ HPO ₄ , and K ₂ B _4.
It is an aqueous solution containing about 3% by mass of O _7, 0.3% by mass of ethyltributylammonium ethylsulfate, and some adiponitrile, propionitrile, and 1,3,6-tricyanohexane. Adjusted to 8. The oil phase is in dissolution equilibrium with the water phase, and its composition is about 28 mass% acrylonitrile and about 62 mass% adiponitrile.

A linear velocity of 1 m /
It was circulated and supplied to a single electrolytic cell so that the time became sec, and electrolysis was performed at a current density of 20 A / dm ² and 50 ° C. Simultaneously with the start of electrolysis, the aqueous phase of the emulsion sent from the electrolytic solution tank to the oil-water separator is kept at about 50 ° C. in the iminodiacetic acid type chelate resin (Lewatit ™ TP20).
7, Bayer Co., Ltd.) K ⁺ type 200CC 6CC / A
The treatment was started at the rate of H and circulated in the electrolytic solution tank.

At the same time, the oil phase was continuously withdrawn, acrylonitrile and water were continuously added so as to maintain the composition of the electrolytic solution, and ethyltributylammoniumethylsulfuric acid dissolved in the oil phase and withdrawn was added at any time. As a result of performing electrolysis for 2000 hours in this manner, the initial electrolysis voltage was 3.
Stable at 9 V, hydrogen contained in the generated gas was 0.16 vol% at the end of electrolysis, and the consumption rate of the cathode was 0.21 m.
g / AH, the consumption rate of the anode was 0.23 mg / AH, and there was no uneven anode corrosion product. 90% yield of adiponitrile based on consumed acrylonitrile,
The yield of 1,3,6-tricyanohexane was 7.5%.

Next, the oil phases obtained by the above electrolysis were collected and subjected to a water extraction treatment to remove acrylonitrile, propionitrile and water by distillation, and then adiponitrile was removed by vacuum distillation. The adiponitrile in this residual is 1
It was 1.5% by mass. The removal of adiponitrile from the residual liquid was carried out by batch distillation of a fraction containing adiponitrile as a main component using a vacuum jacketed distillation column having a diameter of 32 mmφ and an actual number of stages of 5 and the column top temperature at a vacuum degree of 2.0 mmHg. 12
The distillation residue (A) was obtained by first distilling the fraction from 0 to 210 ° C.

The distillation residue (A) was obtained by adding 4.0% by mass of adiponitrile and 84.% of 1,3,6-tricyanohexane.
5% by mass, 5.0% by mass of 3-cyanomethyl-1,5-dicyanopentane, and 6.5% by mass of a high-molecular weight substance, a trinitrile mixture containing a trinitrile compound as a main component (B).
Met. The trinitrile mixture was isolated from the distillation residue (A) using a Smith type laboratory molecular distillation apparatus (manufactured by Shinko Faudler Co., Ltd., type 2, electric heating area 0.032 m ² , glass). Vacuum degree 0.1 mmHg, outer wall heating temperature 180 ° C., distillation residual (A) feed rate 2 g / m
It was operated in. At this time, supply amount 2000g, distilling amount 1
It was 150 g and the distillation residue was 900 g. The distillate has a composition of 1,3,6-tricyanohexane 93.3 mass%, 3
It was a yellow trinitrile mixture (C) consisting of 5.8% by mass of -cyanomethyl-1,5-dicyanopentane and 0.9% by mass of adiponitrile.

Trinitrile mixture (C) obtained above
As a result of measuring the hue, the L value was 98.2 and the a value was -1.
18, the b value was 3.68. The Hazen value of the trinitrile mixture was 400. Add the trinitrile mixture (C) 10 obtained above to a 300 ml eggplant-shaped flask.
Charge 0 g and 80 g of 30% hydrogen peroxide solution at room temperature for 1
The treatment was carried out by stirring vigorously for 00 hours. The liquid was an oil-water two-phase system. After stirring, the oil phase was separated, and the oil phase was dried over anhydrous magnesium sulfate. As a result of measuring the composition of the oil phase, there was no change from the used trinitrile mixture (C), and as a result of measuring the hue, the L value was 99.8 and the a value was −0.
20, the b value was 0.11, and the Hazen value was 100 or less. This oil phase was a trichromatic mixture of low hue which was almost colorless and transparent in appearance.

[0045]

Example 2 In a 200 ml eggplant flask, 50 g of the trinitrile mixture (C) obtained in Example 1, 50 ml of distilled water and activated carbon (Shirasagi (trademark) A manufactured by Takeda Pharmaceutical Co., Ltd.)
2.5 g was added, and the mixture was vigorously stirred at 25 ° C to 30 ° C for 5 hours. The liquid was an oil-water two-phase system. After stirring, filtration was performed, the oil phase was collected, and dried over anhydrous magnesium sulfate. As a result of measuring the composition of the oil phase, this oil phase was not different from the used trinitrile mixture (C), and as a result of measuring the hue, the oil phase had an L value of 100, an a value of -0.17, and a b value. Value is 0.2
2. Hazen value was 100 or less, and it was a trinitrile mixture of low hue which was almost colorless and transparent in appearance.

[0046]

[Example 3] The same operation as in Example 2 was carried out except that the amount of activated carbon was changed to 0.25 g. The obtained trinitrile mixture was not different from the used trinitrile mixture (C), and the hue was measured. As a result, the L value was 99.79, the a value was -0.26, the b value was 0.80, and the Hazen value was Was 100 or less, and it was a low hue trinitrile mixture that was almost colorless and transparent in appearance.

[0047]

Example 4 A cation exchange resin (Amberlyst (registered trademark)) was placed on a glass column having a diameter of 3 cm and a length of 50 cm.
15wet, 120 g of Rohm and Haas Co., Ltd. was charged, and the trinitrile mixture 100 obtained in Example 1 was filled.
g was passed. Using an ozone generator (manufactured by Nippon Ozone Co., Ltd., ON-1-2 type), air having an ozone concentration of about 10 g / Nm ³ was mixed into the obtained trinitrile mixed solution at a flow rate of 30 Nl / hr. 25 ℃ ~ 3 while stirring the liquid
It was blown in at a temperature range of 0 ° C. for 50 hours.

The composition of the obtained trinitrile mixture was the same as that of the used trinitrile mixture (C), and the hue was measured. As a result, the L value was 100, the a value was 0.02, and the b value was 0.02.
The value was 0.03, the Hazen value was 100 or less, and it was a trinitrile mixture of low hue which was almost colorless and transparent in appearance.

[0049]

Comparative Example 1 Using the trinitrile mixture (C) obtained in Example 1, the trinitrile mixture was isolated from the distillation residue (A) in Example 1 by a Smith type laboratory molecular distillation apparatus. Distillation was performed again. The distillation conditions were such that the degree of vacuum was 0.1 mmHg, the heating temperature on the outer wall surface was 175 ° C., and the feed rate of the trinitrile mixture (C) was 1.8 g / min. Supply amount 300g, distillate amount 220g, distillation residue 80g
Met. The distillate is a yellow trinitrile mixture having a composition of 95.3% by mass of 1,3,6-tricyanohexane, 3.6% by mass of 3-cyanomethyl-1,5-dicyanopentane, and 1.1% by mass of adiponitrile. It was (D).

Trinitrile mixture (D) obtained above
As a result of measuring the hue, the L value was 99.3 and the a value was −0.
72, b value was 2.79 and Hazen value was 300.

[0051]

Comparative Example 2 Using the trinitrile mixture (D) obtained in Comparative Example 1, a distillation operation was performed under the same conditions as in Comparative Example. The supply amount was 100 g, the distillate amount was 76 g, and the distillation residue was 24 g. The distillate is a yellow trinitrile mixture having a composition of 95.7% by mass of 1,3,6-tricyanohexane, 3.0% by mass of 3-cyanomethyl-1,5-dicyanopentane, and 1.3% by mass of adiponitrile. (E) was obtained.

As a result of measuring the hue of the above-obtained trinitrile mixture (E), the L value was 99.4 and the a value was -0.7.
3, the b value was 2.72, and there was almost no change in hue.

[0053]

Comparative Example 3 20 g of the trinitrile mixture (E) obtained in Comparative Example 2 and 30 ml of distilled water were vigorously stirred for 1 hour. The oil phase was separated and dried over anhydrous magnesium sulfate.
As a result of measuring the hue of the obtained trinitrile mixture, L
The value was 98.8, the a value was -2.31, and the b value was 2.69, showing almost no change.

[0054]

[Reference Example 1] Internal volume 5 equipped with a reflux condenser and a stirring device
In a 00 ml separable flask, 41 g of a trinitrile mixture having an L value of 99.8, an a value of -0.20 and a b value of 0.11 obtained in Example 1 and 20% caustic soda 3 were added.
00 g was charged and the mixture was heated under reflux for 5 hours to carry out a hydrolysis reaction. After cooling, while cooling with ice, 15.4 g of concentrated sulfuric acid was added dropwise so that the liquid temperature did not exceed 20 ° C.

After completion of the dropping, the solid residue was obtained by completely evaporating to evaporate. Then, in a Soxhlet extractor, extraction operation was performed using ethyl acetate, and the ethyl acetate used under reduced pressure was removed. As a result, a white powdery crystalline solid containing 1,3,6-hexanetricarboxylic acid as a main component was obtained.

[0056]

[Reference Example 2] Internal volume 50 equipped with a reflux condenser and a stirrer
The L obtained in Comparative Example 1 was placed in a 0 ml separable flask.
41 g of a trinitrile mixture having a value of 98.4, an a value of -2.60 and a b value of 9.50 and 20% caustic soda 30
0 g was charged and the mixture was heated under reflux for 5 hours to carry out a hydrolysis reaction. After cooling, while cooling with ice, 15.4 g of concentrated sulfuric acid was added dropwise so that the liquid temperature did not exceed 20 ° C.

After completion of the dropping, the solid residue was obtained by completely evaporating to obtain a solid residue. Then, in a Soxhlet extractor, extraction operation was performed using ethyl acetate, and the ethyl acetate used under reduced pressure was removed. As a result, a yellow colored powdery crystalline solid containing 1,3,6-hexanetricarboxylic acid as a main component was obtained.

[0058]

The trinitrile mixture of the present invention, in particular,
The trinitrile mixture containing 1,3,6-tricyanohexane as a main component can give various derivatives having an improved hue and can be effectively used as various derivatives. According to the production method of the present invention, it can be usefully used as various derivatives, trinitrile mixture of low hue,
In particular, a trinitrile mixture based on 1,3,6-tricyanohexane can be provided.

Claims (6)

[Claims] 1. Obtained from a mixture containing a nitrile compound produced by an electrolytic reduction reaction of acrylonitrile as a main component, the content of the trinitrile compound in the mixture is 85% by mass or more, and the content of adiponitrile is 10% or more.
The lightness index L value of the diethylene glycol dimethyl ether solution having a concentration of 0.10 g / ml is 98% by mass or less.
As described above, the a value of the chromaticness index is -1.0 to 1.
0, b value is -1.0 to 2.0, low hue trinitrile mixture characterized by the above-mentioned. 2. The low hue trinitrile mixture according to claim 1, wherein the content of 1,3,6-tricyanohexane is 85% by mass or more. 3. A nitrile mixture containing adiponitrile as a main component is produced by an electrolytic reduction reaction of acrylonitrile in the presence of an electrolyte, and then adiponitrile is removed from the mixture until the adiponitrile content is 10% by mass or less. A method for producing a low hue trinitrile mixture, which comprises treating a nitrile mixture having a trinitrile compound content of 85% by mass or more by removing components having a boiling point higher than that of the trinitrile compound, with an oxidizing agent. 4. A nitrile mixture containing adiponitrile as a main component is produced by an electrolytic reduction reaction of acrylonitrile in the presence of an electrolyte, and then adiponitrile is removed from the mixture until the adiponitrile content is 10% by mass or less. A method for producing a low hue trinitrile mixture, which comprises treating a nitrile mixture having a trinitrile compound content of 85% by mass or more by removing a component having a boiling point higher than that of the trinitrile compound with a solid adsorbent. 5. A nitrile mixture containing adiponitrile as a main component is produced by an electrolytic reduction reaction of acrylonitrile in the presence of an electrolyte, and then adiponitrile is removed from the mixture until the adiponitrile content is 10% by mass or less. A method for producing a low hue trinitrile mixture, which comprises treating a nitrile mixture having a trinitrile compound content of 85 mass% or more by removing components having a higher boiling point than the trinitrile compound with a solid adsorbent and an oxidant. . 6. The method for producing a low hue trinitrile mixture according to claim 3, wherein the oxidizing agent is ozone or hydrogen peroxide.